TE - cSPF related questions

[khhabib81]

Dear friends,

I have few basic questions related to CSPF and will appreciate if they are answered.

Can we disabled cSPF for specific LSP as we can do with other vendors' router?

If we can, does it mean that we can create LSP from a node 'A' in one ospf area to a node 'B' in different area?

In case we define explicit strict path, does router run cSPF and check TED?

Regards

[shreerampardhy]

Hello Khhabib81,

Please can you explain the scenario in more detail? As far as I am aware, for an RSVP-LSP tunnel to be formed, the headend needs to be aware of the all the interfaces in the path that would satisfy the requirements ( such as bandwith, administrative weight,SRLG, affinity ). The only way for the headend to be aware of this information is via Link state IGPs.Whenever you run the explicit strict path, the TED has to be referred to ensure that the path would satisfy the constraints that you have mentioned. For inter area TE LSP, the headend wont have the information regarding the path constraints in other area. Hence we have to mention the path as loose path pointing towards the ABR between the two areas.

In short, i dont think it is possbile to have an RSVP-LSP without CSPF being run.

Regards,

Shreeram

[Nagendra Kumar Nainar]

Hi,

With verbatim enabled under TE tunnel along with explicit strict path, you can skip TED validation. While I remember trying it in IEGRP topology, I havent tried for inter-area. But considering that it wont check TED, I think it should work fine if you have the explicit stricyt path populated correctly.

HTH,

Nagendra